Television journalists do not make successful politicians. The combative ones stay out of the Commons; mild, conciliatory ones, such as the Conservative MP and junior minister Sir Geoffrey Johnson Smith, who has died aged 86, come in and slip gracefully into mild, conciliatory service. In his TV days in the 1950s, Johnson Smith had been a star of Tonight, a gentle contradiction to Robin Day's prosecuting counsel on ITN.

Born in Glasgow, he was educated at Charterhouse and at Lincoln College, Oxford, where he read philosophy, politics and economics after war service in the Royal Artillery (1942-47). At Oxford, he had been a Labour supporter, but he soon found the social Toryism of Rab Butler and Iain Macleod more attractive than the running battle of Labour. Evicting the sitting Labour MP, Lena Jeger, from marginal Holborn and St Pancras, in central London, in 1959, he retained a good enough profile to take a byelection nomination in serenely Conservative East Grinstead, West Sussex, over the heads of future cabinet ministers, within months of the Conservative defeat in 1964. East Grinstead was duly redistributed into Wealden in 1983 and Johnson Smith, attentive to his constituency and widely liked, came with it.

As a pleaser of people, courteous, moderate, indeed as a fundamentally nice man, he was a natural. He was a comfortable, unaggressive politician. His opinions as a young Tory MP were robustly liberal: defending the banned novel Fanny Hill; openly contemptuous of Kenyan white settlers; and opposed to flogging, a Tory backbench obsession. Johnson Smith was not the sort of bounding personality to make a name. But he had an early run as a PPS at the Board of Trade and Ministry of Pensions (1960-63), as opposition whip (1965) and as a Central Office personage.

It was at this time that his career suffered a long hiccup through one of his few ventures into truculence. As vice-president of the party (candidates), from 1965 to 1970, he had said sharp things about Scientologists. They sued and, following absurd caution from the Heath leadership, Johnson Smith was first shifted to another vice-presidency (youth).

Though the Tories won the 1970 election, he had to wait till the following year for a junior job at defence, and then, in 1972, was moved sideways to a similar status at the civil service department. His time in office was not especially distinguished. His life was further complicated when, in 1973, Kenneth Littlejohn, an ingenious robber who had moved in republican circles in Northern Ireland, claimed that in 1971 he and his brother had been officially approved as spies. He further stated that while wanted by the police, he had passed information about the origins of certain IRA weaponry to Johnson Smith. The meeting had indeed taken place, with Johnson Smith acting properly with approval from the defence secretary. But Littlejohn's information was dismissed as false.

Johnson Smith's backbench contributions after 1974 were sensible and humane, but they had little effect. A warning against premature expansion at Gatwick airport, natural enough in a Sussex member, did not stop its growth. He showed some devotion to the autonomy of local government, a doomed concept at that time. There was also a private member's bill in 1978 to cut back quangos, a position taken by many Tories then.

Johnson Smith could not expect office in the Thatcher government elected in 1979, when he was 55. But he stayed in politics until 2001, chairman or vice-chairman of many things: the select committee on members' interests (1980-95), the Conservative backbench defence committee (1988-93), the British-US parliamentary group and, more substantially, the 1922 Committee (1988-2001).

Having been a defence junior, he retained an interest in the topic, subscribing without abrasion to all the expected Atlanticist certainties. He was a notable defender of Trident missiles. As chairman of the members' interests group, an all-party select committee, he was reliably loyal, notably in defence of Thatcher.

As chairman of the Conservative media group (1980-83), he was on hand to chide the BBC for what he called its Olympian neutrality during the Falklands war. He also called for the privatisation of British Rail in 1988. But he was willing to voice doubts about "rushing to end the BBC licence fee", opposed auctioning off television franchises to the highest bidder; and his chairmanship of the Tory defence group was won as a moderate candidate against the ultra, John Wilkinson.

The automatic knighthood came in 1982 and there was a quiet, respectable business career, much of it related to the media world from which he had come – LWT (Holdings) from 1981, Philips Telecommunications from 1987 – and to PR – Taylor Alden from 1975. Johnson Smith, a sweet-natured man with no taste for conflict, usually had decent and tolerant instincts, but sometimes could do no more than murmur regret at their assured defeat.

He is survived by his wife, Jeanne, whom he married in 1951, and their two sons and daughter.

• Geoffrey Johnson Smith, politician, born 16 April 1924; died 12 August 2010